THE EFFECT OF CHLORAMBUCIL ON THE BIOSYNTHESIS OF THE HMG AND HISTONEH1 CHROMOSOMAL-PROTEINS OF HEP-2 CELLS

The effect of chlorambucil, a bisalkylating agent, on the biosynthesis of the 5% PCA extractable protein fraction of the cancer cell line, H Ep-2, has been analyzed. It was found that the synthesis of all the hi gh mobility group proteins as well as that of the H1 and H1o histone p roteins are inhibited by this agent. HMG 14 and the H1, H1o proteins a re inhibited to the same extent as that reported for the core histones of the same cell line [7], while slightly higher levels of inhibition were found for the HMG 1, 2 and 17 proteins. The proteins, P1 and HMG I exhibited the highest level of inhibition of the entire fraction. T hese findings extend previous findings regarding the histone proteins and may be correlated to a dysfunction in the normal process of chroma tin condensation and a potential cytotoxic effect of this agent during the G2 phase.